M.Goodall, A.Tagg British Aircraft before the Great War (Schiffer)
Deleted by request of (c)Schiffer Publishing
P.Lewis British Aircraft 1809-1914 (Putnam)
Short Tandem Twin
The Tandem Twin of 1911 was known colloquially as the "Vacuum Cleaner", owing to the draught created by its pair of 50 h.p. Gnomes, or the "Gnome Sandwich", because the side-by-side pilot and passenger were seated between the engines. The tractor-pusher machine was Short No. 17 and was built for F. K. McClean, who gave it his private number 11. The Tandem Twin and Triple Twin were the outcome of Horace Short's belief in obtaining plenty of power for his aeroplanes by employing more than one engine. In essence, they were direct developments of the S.27 design and were the first multi-engined machines built in Great Britain and probably the first in the world. The Tandem Twin was bought daring late 1911 by the Admiralty and was used for training naval pilots at the Eastchurch flying-school under its Admiralty number 27. Span, 50 ft. Length, 45 ft. Wing area, 500 sq. ft. Weight loaded, 2,100 lb. Maximum speed, 55 m.p.h.
Short T.3 Triple Twin
Together with the Tandem Twin, the Triple Twin was one of Horace Short's experiments in multi-engined aeroplanes. It was built during mid-1911 for F. K. McClean, who tested it at Eastchurch in September of the year. In the case of the Triple Twin, the front 50 h.p. Gnome engine drove two tractor propellers by means of long chains, while the rear 50 h.p. Gnome acted as a single pusher. All three propellers were of 8 ft. 6 ins. diameter. The machine seated two. In its original form the wings had an equal span of 34 ft. They were soon increased by extensions to an upper span of 50 ft., resulting at the same time in an increase in area from 435 to 500 sq. ft. At the end of 1911 the Triple Twin was used for the training of naval pilots at Eastchurch, and was later given the designation T.3.
Description: Two-seat tractor-pusher biplane. Wooden structure, fabric covered.
Manufacturers: Short Brothers, Eastchurch, Isle of Sheppey, Kent.
Power Plant: Two 50 h.p. Gnomes.
Dimensions: Span, 34 ft. (later 50 ft.). Length, 45 ft. Wing area, 435 sq. ft. (later 500 sq. ft.).
Performance: Maximum speed, 55 m.p.h.
Short Tractor-pusher Monoplane
The second Short monoplane was constructed during 1912 and was nicknamed the "Double Dirty". Two 70 h.p. Gnome engines were fitted, one in front of the pilot and the other behind him. The machine was fitted w ith inflatable flotation bags to enable it to alight on water, and was tested for the Admiralty in September, 1912, by Cdr. C. R. Samson. R.N.
Short Admiralty No. 3
The Admiralty No. 3 was acquired by the Naval Wing of the R.F.C. during 1913. It was a two-seat pusher biplane and was powered by the 80 h.p. Gnome engine. One only was built, and it took its designation from the number allotted to it on entering service. The No. 3 was employed for training pilots at Eastchurch, but, in October, 1914, it was sent out to join Cdr. C. R. Samson's Eastchurch Squadron of the R.N.A.S. in France.
O.Thetford British Naval Aircraft since 1912 (Putnam)
SHORT TANDEM TWIN
This aeroplane, with the Triple Twin the first multi-engined aircraft ever built in Great Britain, was purchased by the Admiralty in 1911 and used at the Naval Flying School at Eastchureh. It was converted from a Short S.27 airframe. It had two 50 hp Gnome rotary engines, one driving a tractor and one a pusher airscrew, the pilot being seated between. Maximum speed, 55 mph. Span, 34 ft 2 in. Length, 40 ft 6 in.
SHORT S.39 TRIPLE TWIN
This early Short biplane, also used by the Naval Flying School at Eastchurch from 1911 (RNAS No.3) was powered by two 50 hp Gnome engines. The front engine drove twin airscrews and the rear engine a single pusher. Maximum speed, 55 mph. Span, 50 ft. Length, 45 ft. In July 1913 it was re-built as a two-seater with no forward stabiliser and a single Gnome pusher and went to Belgium in 1914 with Cdr Samson's Eastchurch Squadron.
Flight, September 9, 1911.
THE NEW SHORT BIPLANE.
To design and construct a new biplane fitted with a 100-h.p. plant consisting of two engines and three propellers, is sufficient proof, if any were needed, that Messrs. Short Brothers do not lack enterprise. Moreover, it is evidence that they have the courage of their convictions, for the machine is a full scale experiment intended to test some of their more recent patents. So far as the framework and planes are concerned, the machine adheres more or less closely to the standard practice of the firm, and thus they are following the very proper course of trying out new things on a basic design that they already know something about.
The new feature is the power plant, which consists of two engines placed fore and aft. The forward engine drives two tractor-screws by means of chains, the after engine is direct coupled to a propeller. The combined power of the equipment is 100-h.p., and both engines are intended to be in operation simultaneously. However, the machine is so designed that either one of its engines will be sufficient to keep the machine flying at a speed of about 36 miles an hour, while with both in operation the speed is expected to be somewhere in the neighbourhood of 55 miles an hour. By so equipping the machine with two entirely independent power plants, the risk attending engine failure is almost entirely obviated, for should one peter out, the pilot will be able to proceed unconcernedly by the aid of the other, and leisurely choose a suitable landing place, where he may descend to make any adjustments to his temporarily disabled engine. This is one advantage that the makers claim for the system. Another is, naturally, the enhanced efficiency of the slow-speed tractor-screws driven by the forward motor, but the third claim is the most interesting of all. Messrs. Short Bros, consider that the draught from these tractor screws will be sufficient to establish a permanent uniform "wind" through the gap of sufficient magnitude to blow out any ordinary gust, and that to this extent they will render the machine far more stable in windy weather than would otherwise be the case. Also, it is anticipated that the efficiency of the planes will be enhanced by working in the propeller draught, which will at all times augment the effective flight speed, and an even more important consideration is that the balancers, which are directly in its wake, will be rendered far more sensitive at slow velocities. It has always been argued in connection with the control of aeroplanes by organs like balancers, which themselves derive their force by flying through the air, that their effectiveness varies with the speed of the machine, and is a minimum when the disturbance is likely to be most dangerous. On the new Short biplane, however, these balancers, by operating in the draught of the tractor screws, will have a minimum useful value that is independent of the speed of flight.
Although these are not all the points that Messrs. Short Bros, are seeking to investigate in their new biplane, they must suffice for the moment, and they are, in any case, sufficient to give weight to our statement that the machine in question is one of exceptional interest and does the makers credit. If we turn from the principles to the machine itself, there is one point on which we feel compelled to make an early remark, which is that the structural work has been finished with all the care that one expects on an aeroplane built to order, and but too seldom finds on one that is built for trial purpose, only. It is, however, characteristic of the firm that their experimental work should be of this description, so we need say no more about its
Most of what it is necessary to know about the design and construction of the machine can be seen at a glance by the aid of the accompanying photographs and drawings, and much of the detail that is invisible can be taken for granted by assuming that it is the same as that already described by us in connection with the standard Short models. Two differences that may be noted, however, are the triple rudder and the small span of the elevator outrigger booms, compared with the span of the elevator itself.
Both engines are seven-cylinder rotary Gnomes, and that in front forms as it were the nose of a car, fashioned somewhat, as it appears at first glance, like the outline of a racing automobile. The pilot sits in this car, and there is room for a passenger alongside him, but although the extra seat is not there yet, we have visions of accommodation being provided for two other passengers behind the pilot if the machine proves anything like as successful as is hoped. The aft motor is situated well behind the back of the car, as one of the photographs shows.
The tractor screws are driven by very long chains, running in tubular guides, and rotate in opposite directions, one of these chains being crossed in order to give the necessary reversal of motion. Wright practice is recalled in the use of these steel guide tubes, and in the shape of the tractors themselves; it affords, in fact, a particularly interesting comparison to note the difference in form between the slow-speed propellers in front and the high-speed propeller behind.
In front of the pilot is a wheel mounted on the top of a pivoted column. Turning the wheel operates the balancers, and a to-and-fro motion of the column controls the elevator. Steering is effected by a pivoted cross-bar under the feet, and this mechanism is fitted in duplicate so that the passenger may work in unison with the pilot.
A point that is worth noting is that the fuel tanks are situated as far away from the engines as is practicable, in order to remove as far as possible the liability of serious accident in the event of an atterrissage brusque. They are also fitted with feed pipes of such design as to ensure a constant supply to the carburettor for any attitude that the machine may assume in flight.
So much is, for the moment, all we need say of the new Short biplane, but the fact that it is an experimental machine affords us the opportunity for remarking that it is by no means indicative in itself of the extent of Short Bros.' experimental work, and we should like to congratulate them on this occasion for the thoroughness with which they investigate stresses and strains, and by every means do their utmost to protect the pilot against mechanical failure in flight, for which they very properly say "there is no excuse."
Flight, September 23, 1911.
FROM THE BRITISH FLYING GROUNDS.
THERE is not a great deal to report, but a first trial has been made, as mentioned below, with the new Short double-engined biplane, fully described in the issue of FLIGHT of the 9th inst.
On Monday Mr. F. C. McClean made the first trial flights in his new Short twin engine biplane, the flights proving very successful, and the machine answering fully the expectations of its constructors. The first trial was made by Mr. McClean alone, who made a short straight flight, in which the machine showed great buoyancy, rising rapidly into the air in spite of the preliminary run being uphill.
Afterwards, with Lieut. Samson on board, Mr. McClean made eight laps of the ground in which he frequently flew with either engine throttled down. A strong feature of the tactics was the large margin of power exhibited by the machine in flight, it being possible to vary the speed considerably, by throttling down either or both engines without causing a descent.
Mr. McClean stated afterwards that he found the warping control very effective and the biplane very steady in flight; it also showed a very flat gliding angle, when the engines were cut off, in this respect, strongly reminding one of the Nieuport monoplanes at the last Gordon-Bennett Race. The speed was estimated at 52 to 54 m.p.h.
Flight, November 4, 1911.
FROM THE BRITISH FLYING GROUNDS.
Royal Aero Club Flying Ground, Eastchurch.
INTEREST centred on Sunday around the trail of another new twin-engine machine which has just been completed in the shops of Messrs. Short Bros., the design of which is included amongst their patents for twin-engine system machines.
No doubt the method of employing the two propellers will be largely criticised, as it has always been an accepted theory that one propeller working directly in the wake of another is not an ideal and efficient arrangement; but, so confident has Mr. H. L. Short been that this system could be made quite efficient and simple, that the present machine was built, and on its first trials fully justified the confidence which the designer had placed in it.
The machine is fitted with two 50-h.p Gnomes, one behind the main planes in the centre line of the machine, with a single propeller, and the other engine directly at the back of the planes on the same axial line as the front engine, also fitted with a single propeller. The nacelle is situated between the two engines and is arranged with thwartship seats and dashboard, and dual control throughout. The engines turn in opposite directions, so that there is no gyroscopic action and no engine torque, as one engine balances the other when both are running at the same speed and give off the same horse-power. The machine flies easily with either engine.
So great has been the success of twin-engine drives, both with three screws, and the latest with two screws, that Messrs. Short Bros, are now commencing to build a machine of 250-h.p., which will have four propellers.
Upon the dashboard of the machine now under review are conveniently arranged a complete set of instruments such as an aviator requires, which include a speed indicator for each engine and an aneroid barometer, the latter specially made for aviation work by Short Bros. Another new feature introduced by the makers is in regard to the petrol supply, which is controlled by a special cock, which in turn is connected to an indicator finger working against a graduated dial, thus enabling the tap to be set to the most suitable opening and the exact position noted - a detail of considerable importance in relation to Gnome engines. As before mentioned, the machine is fitted with dual control, so that it can be operated from either seat, and by a neat arrangement the switches and throttles of the two engines can be worked either separately or both at once by a single movement of the hand, as occasion requires.
Mr. Frank McClean, who piloted the machine on its first run, did not attempt any preliminary ground rolling, but took the machine straight into the air and made a lap of the aerodrome at a height of about 100 feet. On descending he expressed great satisfaction at the behaviour of the machine, which flew extremely well and at a great speed. During the afternoon he made several extended flights, taking in turn Lieut. Samson, R.N., Lieut. H. V. Gerrard (brother of Capt. Gerrard, the aviator) and Mr. J. L. Travers, of Messrs. Short Bros., as passengers. For a final flight, taking with him Lieut. Gregory, R.N., as passenger, Mr. McClean made a long tour of the island, passing over Queenborough and Sheerness, keeping at an altitude of about 600 feet the whole way. The machine exhibited splendid climbing powers, rising with unusual rapidity.